This invention relates to a retort for coal gasification plant and more specifically relates to a retort used in a two stage gas production plant.
A coal gasification plant which employs a two stage process extracts gases from two points in the plant. The gases are extracted firstly from the gasifier and secondly from near the top of the predistilation retort and are known as bottom gas and top gas respectively. Bottom gas is relatively free from coal tars and the like whilst top gas contains a relatively high percentage of tars and it is thus desirous to keep the two gases seperate until the tar has been removed from the top gas. Most prior art retorts use a complex arrangemnt of flues and gas communication passages to draw the bottom gas around the coal in the retort up to near the top of the retort from where it is extracted. The reason bottom gas was drawn up through the retort passages was because it was believed that heat, emitted by the flues carrying the bottom gas, was transmitted to the coal in the retort and contributed significantly to the distillation thereof.
Retorts are usually made from refractory materials and thus constructing the arrangement of flues and gas communication passages is both a complicated and expensive operation. Simplification of the retort allows the introduction of an agitator to break up coal agglomerates when coking coals are employed.
It is an object of the present invention to provide a two stage gasification plant in which the above-described problems are, at least to some extent eliminated.
It is a further object of the invention to provide a retort in which the carbonaceous material in the distillation zone can be agitated in use.